Annotation:
The genomes of many plants, animals, and fungi frequently comprise dispensable B chromosomes that rely upon various chromosomal drive mechanisms to counteract the tendency of non-essential genetic elements to be purged over time. The B chromosome of rye undergoes targeted nondisjunction during first pollen mitosis, favouring segregation into the generative nucleus, thus increasing their numbers over generations. Using a newly-assembled, ~430Mb-long rye B chromosome pseudomolecule, we identified five candidate genes whose role as trans-acting moderators of the chromosomal drive is supported by karyotyping, chromosome drive analysis and comparative RNA-seq. The analyses suggest that rye B gene
DCR28, derived from a functional A chromosome ancestor, evolved on the B chromosome into playing a key role in controlling drive by modifying the normal functioning of microtubules during first pollen mitosis.
Link